In recent years, flexible display technologies have been research hotspots in the area of display technologies. Flexible displays have advantages of being thinner, more shock resistant and lighter, and will be widely applied in commercial and military areas. A flexible display may be defined as a display in which a very thin flexible substrate that can be bent to a curvature radius of a few centimeters or even smaller without impairing the display function of the display panel is used as the substrate of the display panel.